Volume 20, Issue 8, Pages 983-990 (August 2013) Self Resistance to the Atypical Cationic Antimicrobial Peptide Edeine of Brevibacillus brevis Vm4 by the N-Acetyltransferase EdeQ Erin L. Westman, Marie Yan, Nicholas Waglechner, Kalinka Koteva, Gerard D. Wright Chemistry & Biology Volume 20, Issue 8, Pages 983-990 (August 2013) DOI: 10.1016/j.chembiol.2013.06.010 Copyright © 2013 Elsevier Ltd Terms and Conditions
Figure 1 Structures of Edeines A, B, D, and F Two isomers of each type of edeine are known; those in which β-serine is linked to the α-amino group of DAPA are biologically active (isomer 1), and those in which the β-serine is linked to the β-amino group of DAPA are inactive (isomer 2). Edeine nomenclature requires statement of the type of edeine (A, B, D, or F, depending on the structural subunits) as well as the isomer (1 or 2, depending on the linkage of β-serine to the α- or β-amino group of DAPA). For example, the active edeine A isomer 1 can be abbreviated to edeine A1. DAPA, 2,3-diaminopropionic acid; DAHAA, 2,6-diamino-7-hydroxyazaleic acid. Chemistry & Biology 2013 20, 983-990DOI: (10.1016/j.chembiol.2013.06.010) Copyright © 2013 Elsevier Ltd Terms and Conditions
Figure 2 Scale Map of the Edeine Biosynthetic Gene Cluster from B. brevis Vm4 See also Table S1. Chemistry & Biology 2013 20, 983-990DOI: (10.1016/j.chembiol.2013.06.010) Copyright © 2013 Elsevier Ltd Terms and Conditions
Figure 3 Characterization of EdeQ Activity (A) Disk diffusion assay of edeine A after reaction with acetyl-CoA and EdeQ. The lack of a zone of inhibition indicates that edeine A lost its activity against B. subtilis 168 after the N-acetylation reaction. (B) In vitro translation of control GFP by E. coli ribosomes, measured by GFP fluorescence of reactions containing 100 μg/ml of selected antibacterial agents. See also Figure S1. Chemistry & Biology 2013 20, 983-990DOI: (10.1016/j.chembiol.2013.06.010) Copyright © 2013 Elsevier Ltd Terms and Conditions
Figure 4 Structure of Edeine B1 Bound by the Ribosome The guanylspermidine terminus (indicated) does not appear to make contacts with the ribosome, but the DAPA residue (orange carbon backbone) is involved in a turn structure that, if perturbed, may inhibit binding. The amino group of DAPA that is N-aceytlated by EdeQ is indicated (black arrow). Adapted from Protein Data Bank ID code 1I95 (Pioletti et al., 2001); the guanylspermidine terminus was modified to reflect the structure of authentic edeine. Chemistry & Biology 2013 20, 983-990DOI: (10.1016/j.chembiol.2013.06.010) Copyright © 2013 Elsevier Ltd Terms and Conditions
Figure 5 MS/MS Fragmentation of Acetyledeine Interpretation of observed masses from MS/MS fragmentation by correlating observed and expected mass. The location of fragmentation is indicated (dashed lines) and corresponding masses are shown (below dashed lines). See also Figure S2. Chemistry & Biology 2013 20, 983-990DOI: (10.1016/j.chembiol.2013.06.010) Copyright © 2013 Elsevier Ltd Terms and Conditions
Figure 6 1H-NMR Spectra 1H-NMR spectra of edeine A1 (red) and N-acetyledeine A1 (blue). See also Table S2. Chemistry & Biology 2013 20, 983-990DOI: (10.1016/j.chembiol.2013.06.010) Copyright © 2013 Elsevier Ltd Terms and Conditions
Figure 7 Selected HMBC Couplings of N-Acetyledeine A1 (A) Structural diagram of DAPA residue depicting key HMBC couplings. (B) HMBC spectra showing couplings between DAPA or methyl group protons and acetyl carbonyl group (a–d) and between DAPA protons and the backbone carbonyl group (e and f). Observations confirm that the site of acetylation is the DAPA residue (see text for more details). Chemistry & Biology 2013 20, 983-990DOI: (10.1016/j.chembiol.2013.06.010) Copyright © 2013 Elsevier Ltd Terms and Conditions